1. Field of the Invention
This invention generally relates to electro-optical systems for reading indicia of different light reflectivity such as bar code symbols and, more particularly, to adjustably steering a scanning light beam emitted by a light source and/or the field of view of a light detector about three mutually orthogonal axes.
2. Description of Related Art Laser scanner systems and components of the type exemplified by U.S. Pat. Nos. 4,251,798; 4,360,798; 4,369,361; 4,387,297; 4,593,186; 4,496,831; 4,409,470; 4,460,120; 4,607,156; 4,673,803; 4,736,095; 4,758,717; 4,816,660; 4,808,804; 4,816,661; 4,760,248; 4,871,904; 4,806,742; 4,845,350, as well as U.S. application Ser. Nos. 148,669 now U.S. Pat. No. 4,825,057, and 147,708 now U.S. Pat. No. 4,835,374 all of said patents being owned by the assignee of the instant invention and being incorporated by reference herein--have generally been designed to read indicia having parts of different light reflectivity, e.g., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working or reading distance from a hand-held or stationary scanner.
Typically, a light source such as a laser generates a light beam which is optically modified and focused to form a beam spot of a certain size at a working distance relative to a housing and is directed by optical components, including a reflecting mirror, along a light path through an exit port of the housing toward a bar code symbol located in the vicinity of the working distance for reflection from the symbol. A photodetector having a field of view extending across and slightly past the symbol detects light of variable intensity reflected off the symbol and generates electrical signals indicative of the detected light. These electrical signals are decoded into data descriptive of the symbol. A scanning component may be situated in the housing, and is operative to either sweep the beam spot in a scan pattern across the symbol, or to scan the field of view of the photodetector, or simultaneously do both. The scanning component is typically a drive motor operatively connected to the reflecting mirror. The scanning component can also be a charge-coupled device (CCD) array.
In any case, one drawback with such known scanners is that the exit port, also known as a scanning aperture, is stationarily mounted on the housing and faces in a single direction. To change direction, one must move the housing. In some applications, this was found to be a limiting factor, especially in the case of workstations where there was limited counter space. In hand-held scanners, both right- and left-handed operators were not easily accommodated by a scanner having a fixed scanning aperture.
It is known in the art of hand-held bar code scanners, for example, in Japanese Patent No. 02-231689, to adjustably steer a laser beam in a single plane through a stationary exit port on a housing by pivoting a reflecting mirror about a single axis. However, the range was limited, and right- and left-handed operators were not readily accommodated.
It is also known in the art of scanner workstations, for example, in U.S. Pat. No. 5,105,070, to adjustably steer a laser beam in a single plane by rotating an adapter mounted on a desk-top support about a single axis. Again, the limited movement of the laser beam in a single plane did not satisfactorily expand limited counter space.
The components for the light scanning system, including the light source, optics, photodetector, scanning components and an electrical conductor, are mounted together in a common assembly to constitute a compact, lightweight, scan module. The scan module is mounted in an interchangeable, modular manner in housings of different configurations.
For example, the housing can be hand-held and shaped as a cylinder in a so-called flashlight-type configuration, or shaped as a box, or shaped with a gun-like configuration. The housing can be mounted on the back of the operator's arm (see, for example U.S. Pat. No. 4,766,299) or on one or more fingers of the operator's hand, typically with the aid of a strap, a clip, or a glove. The housing can be mounted on the operator's arm, typically adjacent or on the writ. The housing can be mounted in a countertop workstation. The housing can be mounted in a mobile cart, or shopping cart, or, in some cases, even in a stationary installation.
The compact, lightweight nature of the scan module enables myriad other housing configurations to be fashioned. Thus, the scan module can be mounted anywhere on an operator's person, e.g. in a helmet to be worn on the operator's head, in eyeglasses to be worn in front of the operator's eyes, in a shoulder or body harness, etc.